Method for controlling red alder using Nectria ditissima ATCC 74260

ABSTRACT

The control of weed trees in reforestation areas is expensive chemical herbicides and falling into disfavour and ultimately may be banned completely. Moreover, the application of herbicides is labor intensive. A simple, effective solution to the problem is to use a biological method of controlling weed trees in which a wooden charge containing a fungus capable of killing the trees is injected into the trees. Preferably the fungus is indigenous to the area of the trees being treated. Red Alder can be effectively controlled using the fungus Nectria ditissima.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method, apparatus and product forbiologically controlling weed trees.

More specifically, the invention relates to the biological control ofred alder (Alnus rubra Bong) and similar weeds using a fungus of thegenus Nectria, preferably Nectria ditissima.

2. Discussion of the Prior Art

The control of weed trees such as red alder in reforestation areas isexpensive in terms of weeding costs and lost growth potential of forestareas. Chemical herbicides are used to remove the majority of aldersfrom 15 to 40 year old conifer plantations in the Pacific Northwest ofthe United States and contiguous areas of Canada. For example, more than90% of the backlog brushland clearing in British Columbia isaccomplished with Vision (a trademark of Monsanto Corporation forglyphosate). Public perception of chemical herbicides is negative andthere is a distinct possibility that the use of major herbicides willultimately be banned. In fact, herbicides are presently banned on publiclands in several areas including Alberta and Quebec, Canada, U.S. ForestService (Region 3), Sweden and Switzerland. Loss of such chemicals inbacklog operations and plantation clearing will present foresters with amajor problem and forestry firms with substantially higher expensesbecause of bush clearance and replant costs. Moreover, the applicationof presently used herbicides is labor intensive, requiring workers towalk through plantations, remove a strip of bark around each weed tree,and paint a herbicide onto and into the wounds. The circumference ofolder trees is often irregular and the task may require considerabletime. The rapid killing of trees using chemicals results in rapiddegradation of the root nodules, which often contain a surfeit of fixednitrogen, with consequent rapid oxidation of nitrogen. The nitrogenforms gaseous oxide gases which dissipate, becoming unavailable forreplenishment of already scarce forest nitrogen stocks.

GENERAL DESCRIPTION OF THE INVENTION

An object of the present invention is to provide a solution to theproblems involved in the use of chemical herbicides in the form of abiological method of controlling red alder. Of course, the basic methodis equally applicable to other weed trees.

Another object of the invention is to provide a method of the abovedescribed type which while controlling weed trees, does not harmconifers or other desired vegetation.

The above objects are met by a biological method of controlling a weedtree comprising the step of injecting a wooden charge containing afungus capable of killing the tree over an extended period of time intothe tree.

The above described method is carried out using a device for injecting awooden charge into a weed tree, wherein the charge is in the form of anelongated body having tapered ends, comprising elongated, tubular barrelmeans having a closed end and an open end for receiving a plurality ofaxially aligned charges; hammer means on said closed end of said barrelmeans for forming a recess in a tree approximating the shape of thecharge; gate means normally closing said open end of said barrel means;handle means on said open end of the barrel means for moving said gatemeans between the barrel closing and open positions; and spring means inthe closed end of said barrel means for biasing any charges in thebarrel means against said gate means, whereby opening of the gate meanswill permit the discharge of a charge from said barrel means.

The charge referred to in describing the device for carrying out themethod includes an elongated wooden body having tapered ends tofacilitate insertion of the charge into a recess in the tree, and animpregnant of a fungus capable of killing the tree in said body.

The process described herein is not intended to kill trees quickly, butrather over a period of several years. The killing of forestintragrowths of red alder over a five year period will release nitrogenproduced by the symbiosis of alder and the bacterium Frankia slowly suchthat the nitrogen is not volatilized by massive localized growth ofbacteria and more becomes available for the developing conifer forest.This environmentally friendly method of removing red alder from coniferplantations reduces competition to conifers and decreases the time fromnewly planted seedling to harvestable tree. Stated in another manner,the method results in larger and more valuable trees than could beproduced in the same time frame if alder competition was not reduced oreliminated.

In the specific embodiment of the method, the specific biologicalcontrol agent (Nectria ditissima Tul.) used is a native fungus which isfar more effective than other fungi tested once inoculated into a tree.The fungus is successfully inoculated into trees using the device andcharge described hereinafter in greater detail. The fungus Nectriaditissima Tul., and the particular isolate PFC-082 (which has beendeposited under ATCC No. 74260, under the terms of the Budapest Treatyand the accessibility of which will be irrevocably and withoutrestriction or condition released to the public) were chosen afterextensive testing from a number of isolates. The isolate is highlyvirulent as demonstrated in records of tree mortality (not included) andin consistency of successful inoculation and extent of tissue damage(Table 1 below), both of which are significantly different from thecontrol.

In greater detail, the method of the invention involves the followingtwo steps:

As a first or preliminary step, fungus is incubated aseptically on 0.5"diameter wooden plugs or charges having tapered ends and impregnatedwith nutrients (possibly antioxidants and antibacterial agents - asindividual situations dictate).

After 2-3 months of fungus growth the charges are inserted into thestems of alders using the device described herein or a similar device.

In preliminary research, alders of 15 to 40 cm diameter were inoculatedwith a variety of fungi in the final test of a five year series. Theresults are set out in Table 1, which provides an indication of cankeror killed tissue length and the percentage of red alder stems cankeredtwo years after stem inoculation with a variety of biocontrol agents.The isolate numbers in the lefthand column are the inventor'sdesignations.

                  TABLE 1                                                         ______________________________________                                                                        Canker                                        Isolate                 Diam.   length                                                                              % Stems                                 No.      Name           (cm)    (cm)  cankered                                ______________________________________                                        PFC-011  Melanconis     15-20   40    50                                               marginalis     20-25    3    50                                               (Peck.) Wehm.  25-30    2    33                                                              30-35   10    33                                                              35-40    1    17                                      PFC-012  Melanconis     15-20   19    50                                               marginalis     20-25    7    50                                               (Peck.) Wehm.  25-30   26    80                                                              35-40    1    17                                      PFC-FC-1240                                                                            Didymosphaeria 15-20   28    40                                               oregonensis    20-25   10    50                                               Goodling       25-30    3    20                                                              30-35    5    33                                                              35-40    0     0                                      PFC-043  Melanconis     15-20   21    100                                              alni Tul.      20-25   28    100                                                             25-30   10    40                                                              30-35    2    17                                                              35-40    5    17                                      PFC-054  Melanconis     15-20   57    75                                               alni Tul.      20-25   36    50                                                              25-30   11    67                                                              30-35    4    17                                                              35-40    0     0                                      PFC-065  Nectria ditissima                                                                            15-20   12    67                                               Tul.           20-25    5    50                                                              25-30   17    50                                                              30-35    9    33                                                              35-40    4    17                                      PFC-075  Phomopsis sp.  15-20   18    100                                                             20-25   10    50                                                              25-30   10    50                                                              30-35   10    50                                                              35-40   14    50                                      PFC-082  Nectria sp.    15-20   70    60                                                              20-25   60    100                                                             25-30   61    100                                                             30-35   65    100                                                             35-40   50    100                                     PFC-085  Valsna alni Peck.                                                                            15-20   11    33                                                              20-25    8    50                                                              25-30   11    67                                                              30-35   13    40                                                              35-40    2    33                                      PFC-088  Hypoxylon mammatum                                                                           15-20   19    80                                               (Wahl.) J. H. Miller                                                                         20-25    7    50                                                              25-30   19    60                                                              30-35    6    50                                                              35-40    0     0                                      PFC-090  Xylaria hypoxylon                                                                            15-20    4    50                                                              20-25    4    33                                                              25-30   28    50                                                              30-35    9    17                                                              35-40    2    17                                      ______________________________________                                    

It will be noted that the rate of mortality of the trees is inverselyproportional to stem diameter (preliminary data), with cankers (stripsof killed tissues) of 60 to 90 cm length developed in the first 2 yearsand cankers as long as 2 meters developed by the end of 2.5 years, withscattered mortality at that time. The method is not intended for usewith stems<10 cm diam. nor>than 40 cm. It is intended that this methodof control fit into an overall forest management - integrated pestmanagement (IPM) plan, integrated as one component of the standardper-commercial thinning and sanitation procedures applied at 10 to 40years of the tree age, with alder death occurring over a 3 to 5 yearperiod. The results found in Table 1 indicate that isolate PFC-082 isthe fungus which achieves both a consistent high degree of infection andacceptable canker length in red alder stems.

BRIEF DESCRIPTION OF THE DRAWINGS

The device and charge used to carry out the inoculation step of themethod will be described with reference to the accompanying drawing,wherein:

FIG. 1 is a schematic, perspective view of a device for inoculating atree; and

FIG. 2 is a longitudinal sectional view of the device of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to the drawing, the device for inoculating a tree, i.e.placing a charge in a tree includes an elongated tubular barrel 1, witha closed end 2 and an open end 3. A cylindrical hammer body 5 is mountedon the closed end 2 of the barrel 1 by means of a block 6 on such closedend and a pair of screws 7. An elongated rod 9 with a threaded end 10extends through the body 5. The threaded end 10 of the rod 9 engagesthreads in the body 5 for adjusting the length of the head or other end11 extending out of the body 5. The rod 9 is rotated by a knurled head12 on the threaded end 10 of the rod. The rod is fixed in one positionby a nut 13, i.e. the nut limits movement of the threaded end 10 of therod into the body 5. When the head 11 of the rod 9 is hammered against atree trunk, a cylindrical recess is produced in the trunk.

The barrel 1 is adapted to receive a magazine 14 defined by a hardplastic tube. The magazine 14 is loaded with wooden plugs or charges 16previously colonized by a suitable fungus. A spring 17 in one end of themagazine 14 biases the charges 16 towards the open end 3 of thebarrel 1. A small hole 18 in the closed end 2 of the barrel 1 permitsadjustment of the spring tension. The open end 3 of the barrel 1 isnormally closed by a gate 20, which includes an opening 21 (FIG. 1) inthe bottom end thereof. The gate 20 is carried by one end of a handle 23for sliding between the closed position (FIGS. 1 and 2) and an openposition in which the opening 21 is aligned with the open end 24 of themagazine 14. A dovetail or other slide (not shown) can be providedbetween the end 3 of the barrel 1 and the gate 20 for maintaining thegate against the such end of the barrel. The handle 23 is generallyC-shaped, the rear end 26 thereof being pivotally connected to thebarrel 1 by a hinge 27. A second hinge 28 is provided in the top of thehandle, the hinges permitting pivoting of the front end of the handlearound the top of a post 30 mounted on the barrel 1. As the handlerotates around the hinges 27 and 28, and slides on the post 30, the gate20 slides between the closed and open positions. With the gate abuttinga tree trunk, when pressure is applied to the handle 23, the variouspieces of the latter rotate around the hinges 27 and 28 causing the gateto slide upwardly. Thus, the opening 21 is aligned with the open frontend of the magazine 14 whereby a charge 16 can be pushed into thepreformed recess in the tree by the spring 17.

The charge for inoculating and the type of material included within theinoculum (adjuvents) are important to the success of mycoherbicides.Each charge 16 is intended to introduce a biological herbicide, whichhas been proven to be effective, past the outer protective layers of atree, and to provide a nutrient base from which the pathogen caninitiate growth and colonize the weed tree.

Certain microorganisms intended as biocontrol agents must have asufficient nutrient base from which to colonize the target weed tree.Initially, the microbe must be maintained until it begins active growthand enzymes germane to the target tree substratum (wood, bark, sap) canbe mobilized. Thereafter, a good nutrient base in the charge will enableinoculum to colonize host tissues quickly enough to outgrow potentialsecondary organisms. This will vary between zero amendments (i.e., woodblock blank alone) and a wood blank infiltrated with nutrients and avariety of adjuvants, as with certain fastidious microorganisms such asPhacidium gaultheriae. Such additives or adjuvants serve variouspurposes as diverse as generating a microsite favorable to theparticular microbe being used, countering the effects of host tissueoxidants, discouraging the growth of bacteria, chelating ions,inactivating chelating agents in other instances, adjusting pH, anddiscouraging incursions of insects.

From an industrial use basis, the charge 16 must be durable, packagedfor uncomplicated use by forest laborers who will install them, and theymust yield consistent results. Consequently, a solid pellet loaded intoa hard-walled, lightweight tubular plastic magazine 14, many of whichcan be slung in a quiver or pack, with the magazine loaded directly intothe barrel 1 or a similar tool, is the ideal medium for treeinoculation. Dried, lyophilized charges are the ideal answers. However,not all fungi will survive that treatment. Consequently, an alternativeis presented which will prove effective providing the charges are usedpromptly.

The charge 16 must yield consistent results and must be at least nearlyequivalent to chemical herbicides in cost effectiveness. The charge 16is produced from a 1.25 cm diameter dowel rod of straight-grain wood,e.g. Alder or Douglas fir, silica gel, clay, or other porous substance,bonded with a minimum of non-mycotoxic resin in the latter twoinstances, and formed with a jig to produce 2.54 cm length pieces. Thepieces are tapered to yield a semi-rounded nose at either end upon asingle application of the jig yielding a bland.

The blanks are twice-sterilized (24 hr interval between sterilizations)at approximately 15 PSI and 240° F. in an autoclave or similarpressure-heat device, maintained aseptic in a container upon removal andtransferred to a freeze dryer (lyophilizer), where residual moisture isevacuated under vacuum. Thereafter, sterile liquid nutrient mediumappropriate to the fungus to be incubated is introduced aseptically intothe evacuated chamber. The medium may be altered with an antioxidantchemical if the target tree species produces oxidizing chemicals inlarge quantities, anti-bacterial chemicals if the potential use ofrequires such, and other adjuvants affecting the net growth or infectionsuccess of the intended mycoherbicide as required. Air is then admittedthrough a bacteria exclusion filter and the infiltrated blanks are give24 hours to absorb the nutrient-adjuvant fluid mixture. Thereafter, asuspension of spores or comminuted mycelium (as appropriate) of thefungus pathogen intended for use is distributed over the surface of theinfiltrated blanks, and the fungus is permitted to grow and colonize theblanks for an appropriate period and at an appropriate temperature(usually 60-90 days at 20° C.). The resultant mycoherbicide-colonizedblanks are treated in one of two ways:

(1) The infiltrated pieces are surface-dried, coated with presterilizedbeeswax, and the wax is permitted to harden. The finished charges areloaded into gas-sterilized (with ethylene or propylene oxides) hardenedplastic sleeves having internal diameters of 2.75 cm (the magazines 14),capped at both ends, and shipped for use within one week. The magazines14 are manufactured for insertion in the barrel behind the gate 20. Theinoculation opening in the tree has been closed with non-fungitoxicmaterial in preliminary tests, which may or may not be necessary.

(2) The infiltrated pieces are relyophilized, coated with a sugar-soymixture with final consistency similar to that of peanut brittle,allowed to harden, tumbled sufficiently to polish the surfaces of thepieces, then loaded into magazines 14 as above. These pieces areintended for long term storage.

I claim:
 1. A biological method of controlling red alder tree comprisingthe step of injecting a cylindrical charge containing Nectria ditissimaATCC 74260 into the tree.
 2. The method according to claim 1, whereinsaid Nectria ditissima ATCC 74260 is capable of killing the tree over aperiod of several years.
 3. The method according to claim 1, whereinsaid charge has been impregnated with nutrients suitable for growingNectria ditissima ATCC 74260 and wherein said Nectria ditissima ATCC74260 is allowed to grow for two to three months on said charge beforeinjecting said charge into a tree.
 4. The method according to claim 3,wherein said charge has tapered ends.
 5. The method according to claim4, wherein the charge is a dowel rod of alder or douglas fir, or silicagel or clay bonded with a non-mycotoxic resin.
 6. The method accordingto claim 5, wherein the charge is produced by forming a blank of saiddowel rod, sterilizing said blank using heat and pressure, infiltratingthe blank with a nutrient appropriate for the fungus Nectria ditissimaATCC 74260, distributing the fungus over the surface of the infiltratedblank, and permitting the fungus to grow for 60 to 90 days at 20° C. 7.The method according to claim 6, wherein the infiltrated blank issurface dried, coated with presterilized beeswax, and loaded into agas-sterilized, hardened plastic sleeve for storage or shipping beforeuse.